Adjustable resistor of the tubular type



June 14, 1949.

D, F. HASTINGS ET AL ADJUSTABLE RESISTOR OF THE TUBULAR TYPE Filed Nov. 7, 1945- FIG! INVENTORS! DONALD F. HASTINGS AND ROBERT H. WINKLER Patented June 14, 1949 UNITED STATES PAT1=l l;\l"l FF ICE Donald F. Hastings, Fair Lawn, and Robert H.

Winkler, Maplewopd, N. J.,..assignors to HardwickHindlc,:Inc., Newark, N. 'J.

Application November 7, 1945; Serial No.62? 138 s Claims. (Cl. 201-56) This inventionrel'ates'to a resistor construction in which the resistor is of the type having the resistance wire wound on a ceramic spool and held in place thereon by any suitable means such as vitreous enamel with a portion of the wireexposed longitudinallyof the spool tomake a contact track for a contacting device. While 'we are. aware of thefact that many types of resistors of the. general type just mentioned have beenmadegithas been our'experience that much trouble has been encountered in making "and maintain-ing'a good contact with theexposedwire track. This is especially true Where the resistance wire is of a small size in a high resistance unit. Many types of contact devices have been used in the past, butthey'ar'e all open to the objection that they soon wear oil the Wire forming the track surface and thus render 'the'device inoperative, this is particularly so if the contact device has to be shifted frequently on the resistor unit. It is therefore the principal object of our invention to provide a resistor constructic'n in which a rolling-insteadoi a scraping contact can be assured throughout the movement of the contact device on the contact track. In securing this object we obtain better contact and longer life of the resistor. Our improved type of construction will be readily understood by reference to the annexed drawing, wherein:

Figure 1 is a plan view of a portion of a resistor with the contact device positioned thereon.

Figure 2 is a sectional view on the line 2-2 of Figure 1.

Figure 3 is a part-sectional and part-elevational view of the right hand portion of the device shown in Figure 2, showing a modified construction.

Figure 4 is a View similar to Figure 3 of a further modified construction.

Figure 5 is a view similar to Figures 3 and 4 but shows a still further modified construction.

In the various views wherein like numbers refer to corresponding parts, I is a tubular member of suitable ceramic material wound in the usual manner by a resistance wire 2 which is held to the spool I by a vitreous enamel 3. A contact track 4 being left for a contact device to move thereover.

In our improved construction the contact device comprises a band 5 which encompasses or encircles the resistor unit I. The band terminates in ends 6 and I. As shown in Figure 2 the end 6 has a portion 8 extruded to provide sufficient threads for a screw 9 which is adapted to pass through the end I so as to draw the ends B and 1 together into clamping or holding engagement with-theresistor I. The band '5 has a pair of outwardlyextendi-ng spaced lugs 19 and l I which are preferably formed outwardly from the material. of the-band 5. The lugs l0 and II are located on the ba-nd in the same arcuate relationship and each-is provided with a perforation [2 which preferably extends downwardly from its lug intothe circular part "of the band 5 thereby insuring thatthe parts or pins [3 which project from opposite ends of the roller M will be located so that the roller M will always contact with the "track 4 when the band 5 is slipped I alon'gjthe resistor.

Contactmay be made with the band through the medium of the end I which has a hole l5 therein which'may receive a terminal to which a connecting wire is attached.

In the construction as shown in Figure 3, screw 5 is replaced by an eyelet I6 and a spring member H. The amount'of tension which the spring 'exe'rts'de'pendson the amount which the ends of the eyelet are spun over to hold it in operative position. In Figure 4 thefcon'struction is such that the extreme portion 8 need not be used as the screw 9 is supplied with a nut 18 and washer H] to hold a spring I1 in position. With this construction the amount of tension given the spring I! can be readily varied. In Figure 5 the construction is very similar to Figure 4: but in place of the spring I! a spring washer 20 is utilized with a wing nut 21 to adjust the tension of the band 5. However, in either case the construction is such that the band 5 can be readily moved from one position to another and then readily fastened in set position.

Heretofore it has been stated that the wire may be held to the spool by a vitreous enamel but while this way may be considered by some people as the preferred way, it is not the only way and where vitreous enamel is used it sometimes leaves a lump or projection of varying size on the outer surface of the unit and we have found that by the use of spring I! or 20 or equivalent the band 5 may be more readily passed over the lump. It may also be noted that where the resistor spool is wound with fine wire ordinary dragging contact many times will catch into a turn of the wire and rip it loose whereas with our roller contact this difficulty is obviated.

It may be mentioned in passing that the band 5 is made of any suitable material such as A;- hard brass, cadmium plated, while the roller may be also made of /2-hard brass with a substantial plating of silver. We have found this choice of materials and arrangement of parts as described to give excellent satisfaction.

Having thus described our invention, what we claim is:

1. A resistor construction including, in combination with a tubular type resistor having a contact track along the length thereof, a band encircling the resistor with means for holding the band in an operative position on the resistor, said band having a pair of spaced outwardly extending lugs, the lugs having perforations therein and a roller mounted between the lugs by parts positioned in said perforations so the roller will engage and roll on said contact track.

2. A resistor construction including, in combination with a tubular type resistor having a contact track along the length thereof, a band encircling the resistor with means for holding the band in an operative position on the resistor,

said band having a pair of spaced outwardly extending lugs, the lugs having perforations therein, the perforations extending from the lugs into the circular position of the band and a roller for contacting with and rolling on the track mounted between the lugs by pin-type extensions positioned in said perforations.

3. A resistor construction including, in combination with a tubular type resistor having a contact track along the length thereof, a band encircling the resistor with means for holding the band in an operative position on the resistor, said band having a pair of spaced outwardly extending lugs, thrown outwardly in arcuate alignment from the material of the band, the lugs having perforations therein and a roller having parts positioned in the perforations which are positioned so as to assist in holding the roller in good contact engagement with the contact track.

4. A resistor construction as set forth in claim 1 further defined in that the holding means includes a resilient element.

5. A resistor construction as set forth in claim 1 further defined in that the holding means includes a. resilient element with means for vary ing the effect of the resilient element.

6. In a resistor construction in which the resistor wire is wound on a ceramic spool and held thereto by a suitable holding means with a longitudinal portion of the wire exposed to make a contact track along the turns of wire, means for making and always assuring a rolling contact with the track, said means comprising a suitable metal band encompassing the spool with means for adjusting the tension of the band around the spool, spaced lugs projecting outwardly on the band and a roller carried by the lugs in a position to contact with and roll on the track when the band is shifted longitudinally of the resistor.

'7. A resistor construction as set forth in claim 6 further defined in that the lugs have elongated openings therein extending downwardly into the arcuate surface of the band while the roller has axially located pins extending from each end into their cooperative openings.

8. A resistor construction in which the resistor has a resistance wire winding with a contact track, means for making contact with turns of the wire without a tendency to pull on the wire and thereby cause it to be displaced or broken, said means comprising a band of suitable current conducting material encompassing the spool and a cylindrically shaped roller carried by the band transversely of the axis of the spool in contact with the track and to roll over the turns as the band is shifted longitudinally of the spool.

DONALD F. HASTINGS. ROBERT H. WINKLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,793,090 Hite Feb. 17, 1931 1,919,061 Hardwick July 18, 1933 2,288,235 Foley June 30, 1942 2,361,010 Cary et a1. Oct. 24, 1944 

